OUTLINE: Patients receive arsenic trioxide IV daily for 5 days during the first week only and then 2 days a week thereafter. Patients also receive IV or oral dexamethasone on days 1-4 every 4 weeks. Treatment continues in the absence of disease progression or unacceptable toxicity. Disease assessments are conducted every 4 weeks. Patients achieving complete response (CR) receive 2 additional courses of therapy after initial determination of CR.